1. Field of the Invention
The present invention relates generally to an A1 interface in a mobile communication system, and in particular, to an apparatus and method for providing an User Datagram Protocol/Internet Protocol (UDP/IP) based A1 interface.
2. Description of the Related Art
FIG. 1 is a schematic diagram illustrating an A1 and an A2 interface between the Base Station Controllers (BSCs) and a Mobile Switching Center (MSC) in a conventional mobile communication system.
In FIG. 1, existing standards for mobile communication systems (e.g. 3rd Generation Partnership Project 2 (3GPP2) A.S0012-C_v1.0—050224) clarify that a Signaling System 7 (SS7) or an IP-based Stream Control Transmission Protocol/User Datagram Protocol (SCTP/UDP) is used as a communication protocol for A1 interfaces using E1/T1 links in a hardware layer between BSCs 110 and 120 and an MSC 130.
The A1 interface carries signaling information between the BSCs 110 and 120 and the MSC 130 to control user traffic for which the A2 interface provides a path. Depending on system configuration, the BSCs 110 and 120 may include Base Transceiver Systems (BTSs), respectively, and the MSC 130 also may have a Media Gateway Controller (MGC) and a Media Gateway (MG) 135. In a structure where a media processor and a media controller are separately configured, the MGC serves as the media controller and the MG 135 serves as the media processor. The MGC 130 uses the Megaco Protocol in H.248.
FIG. 2 is a schematic diagram illustrating a protocol stack for the A1 interface in a conventional mobile communication system.
In FIG. 2, the A1 interface uses the E1/T1 links 210 in a physical layer and the SS7 as a data link layer protocol. The Signaling Connection Control Part/Message Transfer Part (SCCP/MTP) 250 and 255 is a signal control-related protocol of the SS7.
The Base Station Application Parts (BSAPs) 220 and 225 are divided into a Direct Transfer Application Part (DTAP) and a Base Station Management Application Part (BSMAP). The DTAP is a protocol by which the BSCs 110 and 120 send messages received from the Mobile Stations (MSs) to the MSC 130. The BSMAP is a protocol for processing A1 interface messages between the BSCs 110 and 120 and the MSC 130.
The SS7 manages links, but with limitations to its management range. The SCTP also has the drawbacks of delay and low rate because it is connection-oriented.
FIG. 3 is a flow diagram illustrating a procedure for establishing an A1 interface connection in a conventional mobile communication system.
In FIG. 3, the A1 interface connection setup procedure between a BSC SCCP and an MSC SCCP is divided into a connection setup step 310, a data transmission step 320, and a connection release step 330. The connection setup 310 and the connection release 330 may cause delay.
Along with the introduction of the concept of an ALL(All) IP (Internet Protocol) and the evolution of the mobile communication system to the ALL IP, the development trend is that the MSC 130 supports transmission of a large volume of data at higher data rates and the BSCs 110 and 120 are miniaturized. In this context, one MSC 130 needs to accommodate tens of thousands of BSCs.
However, a Transmission Control Protocol (TCP) or an SCTP, which supports connection management in an IP network, suffers from increased delay, increased processing overhead, and weak multimedia support.
Accordingly, there exists a need for a method for reducing delay and overhead and enforcing support for multimedia by use of a non-connection-oriented protocol which takes advantage of the connection-oriented protocol in terms of connection setup speed and transmission rate and whose reliability is ensured owing to the development of networks and hardware, despite its probability of data loss attributed to the non-connection orientation.